Free struct when kref becomes 0.

Signed-off-by: Andy Grover <agro...@redhat.com>
---
 drivers/target/target_core_pr.c   |   99 +++++++++++++++---------------------
 include/target/target_core_base.h |    2 +-
 2 files changed, 42 insertions(+), 59 deletions(-)

diff --git a/drivers/target/target_core_pr.c b/drivers/target/target_core_pr.c
index 9155df0..17a4c3b 100644
--- a/drivers/target/target_core_pr.c
+++ b/drivers/target/target_core_pr.c
@@ -75,6 +75,17 @@ enum preempt_type {
        PREEMPT_AND_ABORT,
 };
 
+static void release_pr_reg(struct kref *kref)
+{
+       struct t10_pr_registration *pr_reg = container_of(kref,
+                                                         struct 
t10_pr_registration, refcount);
+
+       kmem_cache_free(t10_pr_reg_cache, pr_reg);
+}
+
+#define get_pr_reg(x) kref_get(&x->refcount)
+#define put_pr_reg(x) kref_put(&x->refcount, release_pr_reg)
+
 static void __core_scsi3_complete_pro_release(struct se_device *, struct 
se_node_acl *,
                        struct t10_pr_registration *, int);
 
@@ -109,7 +120,6 @@ target_scsi2_reservation_check(struct se_cmd *cmd)
 
 static struct t10_pr_registration *core_scsi3_locate_pr_reg(struct se_device *,
                                        struct se_node_acl *, struct se_session 
*);
-static void core_scsi3_put_pr_reg(struct t10_pr_registration *);
 
 static int target_check_scsi2_reservation_conflict(struct se_cmd *cmd)
 {
@@ -144,17 +154,17 @@ static int target_check_scsi2_reservation_conflict(struct 
se_cmd *cmd)
                 * as defined in SPC-2.
                 */
                if (pr_reg->pr_res_holder) {
-                       core_scsi3_put_pr_reg(pr_reg);
+                       put_pr_reg(pr_reg);
                        return 1;
                }
                if ((pr_reg->pr_res_type == PR_TYPE_WRITE_EXCLUSIVE_REGONLY) ||
                    (pr_reg->pr_res_type == PR_TYPE_EXCLUSIVE_ACCESS_REGONLY) ||
                    (pr_reg->pr_res_type == PR_TYPE_WRITE_EXCLUSIVE_ALLREG) ||
                    (pr_reg->pr_res_type == PR_TYPE_EXCLUSIVE_ACCESS_ALLREG)) {
-                       core_scsi3_put_pr_reg(pr_reg);
+                       put_pr_reg(pr_reg);
                        return 1;
                }
-               core_scsi3_put_pr_reg(pr_reg);
+               put_pr_reg(pr_reg);
                conflict = 1;
        } else {
                /*
@@ -611,7 +621,7 @@ static struct t10_pr_registration 
*__core_scsi3_do_alloc_registration(
        INIT_LIST_HEAD(&pr_reg->pr_reg_aptpl_list);
        INIT_LIST_HEAD(&pr_reg->pr_reg_atp_list);
        INIT_LIST_HEAD(&pr_reg->pr_reg_atp_mem_list);
-       atomic_set(&pr_reg->pr_res_holders, 0);
+       kref_init(&pr_reg->refcount);
        pr_reg->pr_reg_nacl = nacl;
        pr_reg->pr_reg_deve = deve;
        pr_reg->pr_res_mapped_lun = deve->mapped_lun;
@@ -795,7 +805,7 @@ int core_scsi3_alloc_aptpl_registration(
        INIT_LIST_HEAD(&pr_reg->pr_reg_aptpl_list);
        INIT_LIST_HEAD(&pr_reg->pr_reg_atp_list);
        INIT_LIST_HEAD(&pr_reg->pr_reg_atp_mem_list);
-       atomic_set(&pr_reg->pr_res_holders, 0);
+       kref_init(&pr_reg->refcount);
        pr_reg->pr_reg_nacl = NULL;
        pr_reg->pr_reg_deve = NULL;
        pr_reg->pr_res_mapped_lun = mapped_lun;
@@ -1102,8 +1112,7 @@ static struct t10_pr_registration 
*__core_scsi3_locate_pr_reg(
                                if (dev->dev_attrib.enforce_pr_isids)
                                        continue;
                        }
-                       atomic_inc(&pr_reg->pr_res_holders);
-                       smp_mb__after_atomic_inc();
+                       get_pr_reg(pr_reg);
                        spin_unlock(&pr_tmpl->registration_lock);
                        return pr_reg;
                }
@@ -1117,8 +1126,7 @@ static struct t10_pr_registration 
*__core_scsi3_locate_pr_reg(
                if (strcmp(isid, pr_reg->pr_reg_isid))
                        continue;
 
-               atomic_inc(&pr_reg->pr_res_holders);
-               smp_mb__after_atomic_inc();
+               get_pr_reg(pr_reg);
                spin_unlock(&pr_tmpl->registration_lock);
                return pr_reg;
        }
@@ -1145,12 +1153,6 @@ static struct t10_pr_registration 
*core_scsi3_locate_pr_reg(
        return __core_scsi3_locate_pr_reg(dev, nacl, isid_ptr);
 }
 
-static void core_scsi3_put_pr_reg(struct t10_pr_registration *pr_reg)
-{
-       atomic_dec(&pr_reg->pr_res_holders);
-       smp_mb__after_atomic_dec();
-}
-
 static int core_scsi3_check_implicit_release(
        struct se_device *dev,
        struct t10_pr_registration *pr_reg)
@@ -1213,7 +1215,6 @@ static void __core_scsi3_free_registration(
 {
        struct target_core_fabric_ops *tfo =
                        pr_reg->pr_reg_nacl->se_tpg->se_tpg_tfo;
-       struct t10_reservation *pr_tmpl = &dev->t10_pr;
        char i_buf[PR_REG_ISID_ID_LEN];
 
        memset(i_buf, 0, PR_REG_ISID_ID_LEN);
@@ -1227,20 +1228,7 @@ static void __core_scsi3_free_registration(
         * so call core_scsi3_put_pr_reg() to decrement our reference.
         */
        if (dec_holders)
-               core_scsi3_put_pr_reg(pr_reg);
-       /*
-        * Wait until all reference from any other I_T nexuses for this
-        * *pr_reg have been released.  Because list_del() is called above,
-        * the last core_scsi3_put_pr_reg(pr_reg) will release this reference
-        * count back to zero, and we release *pr_reg.
-        */
-       while (atomic_read(&pr_reg->pr_res_holders) != 0) {
-               spin_unlock(&pr_tmpl->registration_lock);
-               pr_debug("SPC-3 PR [%s] waiting for pr_res_holders\n",
-                               tfo->get_fabric_name());
-               cpu_relax();
-               spin_lock(&pr_tmpl->registration_lock);
-       }
+               put_pr_reg(pr_reg);
 
        pr_debug("SPC-3 PR [%s] Service Action: UNREGISTER Initiator"
                " Node: %s%s\n", tfo->get_fabric_name(),
@@ -1254,17 +1242,14 @@ static void __core_scsi3_free_registration(
                " 0x%08x\n", tfo->get_fabric_name(), pr_reg->pr_res_key,
                pr_reg->pr_res_generation);
 
-       if (!preempt_and_abort_list) {
-               pr_reg->pr_reg_deve = NULL;
-               pr_reg->pr_reg_nacl = NULL;
-               kmem_cache_free(t10_pr_reg_cache, pr_reg);
-               return;
-       }
        /*
         * For PREEMPT_AND_ABORT, the list of *pr_reg in preempt_and_abort_list
         * are released once the ABORT_TASK_SET has completed..
         */
-       list_add_tail(&pr_reg->pr_reg_abort_list, preempt_and_abort_list);
+       if (preempt_and_abort_list)
+               list_add_tail(&pr_reg->pr_reg_abort_list, 
preempt_and_abort_list);
+       else
+               put_pr_reg(pr_reg);
 }
 
 void core_scsi3_free_pr_reg_from_nacl(
@@ -1653,7 +1638,7 @@ core_scsi3_decode_spec_i_port(
                pr_reg_e = __core_scsi3_locate_pr_reg(dev, dest_node_acl,
                                        iport_ptr);
                if (pr_reg_e) {
-                       core_scsi3_put_pr_reg(pr_reg_e);
+                       put_pr_reg(pr_reg_e);
                        core_scsi3_lunacl_undepend_item(dest_se_deve);
                        core_scsi3_nodeacl_undepend_item(dest_node_acl);
                        core_scsi3_tpg_undepend_item(dest_tpg);
@@ -2181,7 +2166,7 @@ core_scsi3_emulate_pro_register(struct se_cmd *cmd, u64 
res_key, u64 sa_res_key,
        ret = core_scsi3_update_and_write_aptpl(dev, aptpl);
 
 out:
-       core_scsi3_put_pr_reg(pr_reg);
+       put_pr_reg(pr_reg);
        return ret;
 }
 
@@ -2359,7 +2344,7 @@ core_scsi3_pro_reserve(struct se_cmd *cmd, int type, int 
scope, u64 res_key)
 
        ret = 0;
 out_put_pr_reg:
-       core_scsi3_put_pr_reg(pr_reg);
+       put_pr_reg(pr_reg);
        return ret;
 }
 
@@ -2573,7 +2558,7 @@ write_aptpl:
                core_scsi3_update_and_write_aptpl(cmd->se_dev, true);
 
 out_put_pr_reg:
-       core_scsi3_put_pr_reg(pr_reg);
+       put_pr_reg(pr_reg);
        return ret;
 }
 
@@ -2613,7 +2598,7 @@ core_scsi3_emulate_pro_clear(struct se_cmd *cmd, u64 
res_key)
                        " res_key: 0x%016Lx does not match"
                        " existing SA REGISTER res_key:"
                        " 0x%016Lx\n", res_key, pr_reg_n->pr_res_key);
-               core_scsi3_put_pr_reg(pr_reg_n);
+               put_pr_reg(pr_reg_n);
                return TCM_RESERVATION_CONFLICT;
        }
        /*
@@ -2757,12 +2742,12 @@ core_scsi3_pro_preempt(struct se_cmd *cmd, int type, 
int scope, u64 res_key,
                return TCM_RESERVATION_CONFLICT;
        }
        if (pr_reg_n->pr_res_key != res_key) {
-               core_scsi3_put_pr_reg(pr_reg_n);
+               put_pr_reg(pr_reg_n);
                return TCM_RESERVATION_CONFLICT;
        }
        if (scope != PR_SCOPE_LU_SCOPE) {
                pr_err("SPC-3 PR: Illegal SCOPE: 0x%02x\n", scope);
-               core_scsi3_put_pr_reg(pr_reg_n);
+               put_pr_reg(pr_reg_n);
                return TCM_INVALID_PARAMETER_LIST;
        }
 
@@ -2775,7 +2760,7 @@ core_scsi3_pro_preempt(struct se_cmd *cmd, int type, int 
scope, u64 res_key,
 
        if (!all_reg && !sa_res_key) {
                spin_unlock(&dev->dev_reservation_lock);
-               core_scsi3_put_pr_reg(pr_reg_n);
+               put_pr_reg(pr_reg_n);
                return TCM_INVALID_PARAMETER_LIST;
        }
        /*
@@ -2869,7 +2854,7 @@ core_scsi3_pro_preempt(struct se_cmd *cmd, int type, int 
scope, u64 res_key,
                 */
                if (!released_regs) {
                        spin_unlock(&dev->dev_reservation_lock);
-                       core_scsi3_put_pr_reg(pr_reg_n);
+                       put_pr_reg(pr_reg_n);
                        return TCM_RESERVATION_CONFLICT;
                }
                /*
@@ -2891,7 +2876,7 @@ core_scsi3_pro_preempt(struct se_cmd *cmd, int type, int 
scope, u64 res_key,
                if (pr_tmpl->pr_aptpl_active)
                        core_scsi3_update_and_write_aptpl(cmd->se_dev, true);
 
-               core_scsi3_put_pr_reg(pr_reg_n);
+               put_pr_reg(pr_reg_n);
                core_scsi3_pr_generation(cmd->se_dev);
                return 0;
        }
@@ -3020,7 +3005,7 @@ core_scsi3_pro_preempt(struct se_cmd *cmd, int type, int 
scope, u64 res_key,
        if (pr_tmpl->pr_aptpl_active)
                core_scsi3_update_and_write_aptpl(cmd->se_dev, true);
 
-       core_scsi3_put_pr_reg(pr_reg_n);
+       put_pr_reg(pr_reg_n);
        core_scsi3_pr_generation(cmd->se_dev);
        return 0;
 }
@@ -3442,13 +3427,13 @@ after_iport_check:
                __core_scsi3_free_registration(dev, pr_reg, NULL, 1);
                spin_unlock(&pr_tmpl->registration_lock);
        } else
-               core_scsi3_put_pr_reg(pr_reg);
+               put_pr_reg(pr_reg);
 
        core_scsi3_update_and_write_aptpl(cmd->se_dev, aptpl);
 
        transport_kunmap_data_sg(cmd);
 
-       core_scsi3_put_pr_reg(dest_pr_reg);
+       put_pr_reg(dest_pr_reg);
        return 0;
 out:
        if (buf)
@@ -3460,7 +3445,7 @@ out:
        core_scsi3_tpg_undepend_item(dest_se_tpg);
 
 out_put_pr_reg:
-       core_scsi3_put_pr_reg(pr_reg);
+       put_pr_reg(pr_reg);
        return ret;
 }
 
@@ -3862,8 +3847,7 @@ core_scsi3_pri_read_full_status(struct se_cmd *cmd)
                se_tpg = pr_reg->pr_reg_nacl->se_tpg;
                add_desc_len = 0;
 
-               atomic_inc(&pr_reg->pr_res_holders);
-               smp_mb__after_atomic_inc();
+               get_pr_reg(pr_reg);
                spin_unlock(&pr_tmpl->registration_lock);
                /*
                 * Determine expected length of $FABRIC_MOD specific
@@ -3876,8 +3860,7 @@ core_scsi3_pri_read_full_status(struct se_cmd *cmd)
                        pr_warn("SPC-3 PRIN READ_FULL_STATUS ran"
                                " out of buffer: %d\n", cmd->data_length);
                        spin_lock(&pr_tmpl->registration_lock);
-                       atomic_dec(&pr_reg->pr_res_holders);
-                       smp_mb__after_atomic_dec();
+                       put_pr_reg(pr_reg);
                        break;
                }
                /*
@@ -3938,8 +3921,8 @@ core_scsi3_pri_read_full_status(struct se_cmd *cmd)
                                se_nacl, pr_reg, &format_code, &buf[off+4]);
 
                spin_lock(&pr_tmpl->registration_lock);
-               atomic_dec(&pr_reg->pr_res_holders);
-               smp_mb__after_atomic_dec();
+               put_pr_reg(pr_reg);
+
                /*
                 * Set the ADDITIONAL DESCRIPTOR LENGTH
                 */
diff --git a/include/target/target_core_base.h 
b/include/target/target_core_base.h
index 6bf1da9..513429a 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -363,7 +363,7 @@ struct t10_pr_registration {
        u32 pr_res_generation;
        u64 pr_reg_bin_isid;
        u64 pr_res_key;
-       atomic_t pr_res_holders;
+       struct kref refcount;
        struct se_node_acl *pr_reg_nacl;
        struct se_dev_entry *pr_reg_deve;
        struct se_lun *pr_reg_tg_pt_lun;
-- 
1.7.1

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